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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Olivier Matz <olivier.matz@6wind.com>, dev@dpdk.org
Cc: Chenbo Xia <chenbo.xia@intel.com>,
	Zhihong Wang <zhihong.wang@intel.com>,
	 Flavio Leitner <fbl@sysclose.org>, yang_y_yi <yang_y_yi@163.com>,
Subject: Re: [dpdk-dev] [PATCH] vhost: fix external mbuf creation
Date: Fri, 9 Oct 2020 09:15:57 +0200
Message-ID: <d00a8253-81c6-fcf6-7aa1-6959648b7cc7@redhat.com> (raw)
In-Reply-To: <20201007125318.9850-1-olivier.matz@6wind.com>

On 10/7/20 2:53 PM, Olivier Matz wrote:
> In virtio_dev_extbuf_alloc(), the shinfo structure used to store
> the reference counter and the free callback of the external buffer
> is by default stored inside the mbuf data.
> This is wrong because the mbuf (and its data) can be freed before
> the external buffer, for instance in the following situation:
>   pkt2 = rte_pktmbuf_alloc(mp);
>   rte_pktmbuf_attach(pkt2, pkt);
>   rte_pktmbuf_free(pkt);
> After this, pkt is freed, but it still contains shinfo, which is
> referenced by pkt2.
> Fix this by always storing the shinfo beside the external buffer.
> Fixes: c3ff0ac70acb ("vhost: improve performance by supporting large buffer")
> Cc: stable@dpdk.org
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
> Hi,
> I found this issue by code review while discussing about this
> patchset [1]. I did not tested the patch, but as I'm only removing
> one path among the two, I don't expect that it breaks anything.
> [1] http://inbox.dpdk.org/dev/20200730120900.108232-1-yang_y_yi@163.com/
> Regards,
> Olivier
>  lib/librte_vhost/virtio_net.c | 30 ++++++++----------------------
>  1 file changed, 8 insertions(+), 22 deletions(-)

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>


  reply	other threads:[~2020-10-09  7:16 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-07 12:53 Olivier Matz
2020-10-09  7:15 ` Maxime Coquelin [this message]
2020-10-09  7:24 ` Maxime Coquelin
2020-10-09  8:47 ` yang_y_yi
2020-10-09  9:04 ` yang_y_yi

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